U.S. patent application number 13/122810 was filed with the patent office on 2011-08-11 for method for producing methacrylated benzophenones.
This patent application is currently assigned to Evonik Roehm GmbH. Invention is credited to Christine Maria Breiner, Wolfgang Klesse, Joachim Knebel, Gerold Schmitt.
Application Number | 20110196169 13/122810 |
Document ID | / |
Family ID | 41664816 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110196169 |
Kind Code |
A1 |
Knebel; Joachim ; et
al. |
August 11, 2011 |
METHOD FOR PRODUCING METHACRYLATED BENZOPHENONES
Abstract
The invention relates to a method for producing methacrylated
benzophenones and to the uses thereof.
Inventors: |
Knebel; Joachim;
(Alsbach-Haehnlein, DE) ; Klesse; Wolfgang;
(Mainz, DE) ; Breiner; Christine Maria;
(Laudenbach, DE) ; Schmitt; Gerold;
(Aschaffenburg, DE) |
Assignee: |
Evonik Roehm GmbH
Darmstadt
DE
|
Family ID: |
41664816 |
Appl. No.: |
13/122810 |
Filed: |
November 19, 2009 |
PCT Filed: |
November 19, 2009 |
PCT NO: |
PCT/EP2009/065431 |
371 Date: |
April 6, 2011 |
Current U.S.
Class: |
560/140 |
Current CPC
Class: |
C07C 67/08 20130101;
C07C 67/08 20130101; C07C 69/54 20130101 |
Class at
Publication: |
560/140 |
International
Class: |
C07C 69/76 20060101
C07C069/76 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2008 |
DE |
102008054611.9 |
Claims
1. Process for preparing benzophenone (meth)acrylates,
characterized in that hydroxybenzophenones and (meth)acrylic
anhydride are reacted in the presence of catalytic amounts of acid,
then the catalyst is neutralized, and subsequently the crude
monomer is purified.
2. Process according to claim 1, characterized in that
4-hydroxybenzophenone and (meth)acrylic anhydride are reacted in
the presence of catalytic amounts of acid, which are then
neutralized with aqueous bases, and subsequently the soluble
impurities in the [(meth)acryloyloxy]benzophenone melt are
dissolved by addition of water.
3. Process according to claim 2, characterized in that reaction
takes place in the presence of a catalytic amount of concentrated
sulphuric acid, of an alkylsulphonic or arylsulphonic acid.
4. Process according to claim 1, characterized in that
neutralization is carried out with aqueous alkali metal hydroxide
solution or ammonia solution.
5. Process according to claim 1, characterized in that the reaction
takes place over 4-8 hours at 50 to 120.degree. C.
6. Process according to claim 1, characterized in that the
[(meth)acryloyloxy]benzophenone is precipitated by addition of
excess water to the reaction mixture and is isolated in solid form
by filtration.
7. Process according to claim 1, characterized in that the
[(meth)acryloyloxy]benzophenone, as a result of addition of a
liquid (meth)acrylic ester or styrene into the reaction mixture, is
used as a solution in that ester.
8. Use of benzophenone (meth)acrylates according to claim 1 as
comonomer for polymerization reactions.
9. Use of benzophenone (meth)acrylates for the subsequent
photocrosslinking of polymers.
10. Use of benzophenone methacrylates as polymeric photoinitiators.
Description
[0001] The invention relates to a process for preparing
methacrylated benzophenones and to the uses thereof.
[0002] Described in the state of the art is a methacrylic anhydride
process for preparing the above-stated esters (JP2003261506,
Mitsubishi Rayon). Triethylamine is used as catalyst. Since the
amine forms a salt with the methacrylic acid produced during the
reaction, it must be made equimolar with respect to the
benzophenone. Accordingly, equimolar quantities of salt are
obtained, which require disposal as waste. Consequently the process
is not very economical.
[0003] Further methods of the prior art are the reaction of
methacryloyl chloride with hydroxy-functional benzophenone, and the
reaction of this raw material with glycidyl methacrylate. When
using methacryloyl chloride it is necessary to take account of the
corrosive and caustic properties. On contact with water, moreover,
HCl is released.
[0004] DE 1720603 describes a process for preparing aqueous
dispersions of readily crosslinkable polymers. In that process,
acrylic and methacrylic esters are copolymerized with photoactive,
olefinically unsaturated monomers, where appropriate with the
accompanying use of photoactive, non-ionogenic emulsifiers.
[0005] EP 0346788 describes a process for preparing
radiation-sensitive carbamoylbenzo- and -acetophenones having at
least one methacrylate or acrylate end group. That process reacts
isocyanatoalkyl (meth)acrylates with hydroxyacetophenones or
hydroxybenzophenones, using a basic catalyst. It is necessary to
operate in the absence of moisture. Moreover, only dried,
non-nucleophilic solvents can be used.
[0006] The object was to provide an improved process for preparing
(meth)acrylic esters of hydroxy-functional benzophenones.
[0007] The object has been achieved by a process for preparing
benzophenone (meth)acrylates, characterized in that
hydroxybenzophenones and (meth)acrylic anhydride are reacted in the
presence of catalytic amounts of acid, then the catalyst is
neutralized, and subsequently the crude monomer is purified.
[0008] The notation "(meth)acrylate" here denotes methacrylate,
such as methyl methacrylate, ethyl methacrylate, etc., and
acrylate, such as methyl acrylate, ethyl acrylate, etc., and also
mixtures of both.
[0009] Surprisingly it has been found that, with the process of the
invention, high conversions are achieved, and the amount of
by-products is greatly reduced. It has been found that the process
of the invention is burdened only by a low salt load, which comes
about when the catalyst acid is neutralized in the course of
work-up. The by-product methacrylic acid can be used as a comonomer
in the subsequent polymerization of the benzophenone monomer, or
can be recycled for the preparation of new methacrylic
anhydride.
[0010] The reaction can take place in the presence of common
alkylsulphonic or arylsulphonic acids, preferably with sulphuric
acid.
[0011] Preference is given to reacting 4-hydroxybenzophenone and
(meth)acrylic anhydride in the presence of catalytic amounts of
concentrated sulphuric acid.
[0012] (Meth)acrylic anhydride is added in a slight excess relative
to the hydroxybenzophenone. The reaction takes place at
temperatures between 50 to 120.degree. C., preferably at 80.degree.
C. to 100.degree. C., over 4 to 8 hours, preferably over 5.5 to 6.5
hours.
[0013] The catalytically employed acid is neutralized with aqueous
bases, preferably with alkali metal hydroxide solution or ammonia
solution.
[0014] The subsequent work-up of the crude monomer takes place by
addition of water. In this way, the impurities are dissolved and
can be separated off without problems. The water-soluble impurities
of the [(meth)acryloyloxy]benzophenone melt are removed preferably
by the addition of water.
[0015] [(Meth)acryloyloxy]benzophenone is precipitated by the
addition of excess water into the reaction mixture, and is isolated
in solid form by filtration.
[0016] The benzophenone (meth)acrylates, prepared in high purity,
can be stored and reacted further in solution with methyl
methacrylate, n-butyl methacrylate, isobutyl methacrylate or
styrene.
[0017] Benzophenone (meth)acrylates can be used for subsequent
photocrosslinking of polymers by daylight or UV light, and also as
polymeric photoinitiators.
[0018] The benzophenone (meth)acrylates can be used, furthermore,
as comonomer for polymerization reactions.
[0019] The examples given below are given for better illustration
of the present invention, but are not apt to restrict the invention
to the features disclosed herein.
EXAMPLES
Example 1
##STR00001##
[0020] Apparatus:
[0021] 4 l four-neck round-bottomed flask with mechanical stirrer,
reflux condenser, Pt100 temperature sensor, air introduction tube,
Anschutz attachment, dropping funnel, electrically heated oil
bath
Batch:
[0022] 3.5 mol of 4-hydroxybenzophenone, 99.7%: 695.9 g
[0023] 3.85 mol of methacrylic anhydride (stabilized with 2000 ppm
of 2,4-dimethyl-6-tert-butylphenol): 618.4 g
[0024] 0.020 mol of concentred sulphuric acid: 1.99 g
[0025] 1864 mg of hydroquinone monomethyl ether
[0026] 932 mg of 2,4-dimethyl-6-tert-butylphenol
[0027] Neutralization of the catalyst acid with 1.8 g of sodium
hydroxide in solution in 10 g of water
[0028] Esterification of the excess methacrylic anhydride with 22.4
g of methanol Theoretical yield: 930.0 g
Procedure:
[0029] The batch was weighed out completely and then heated to
90.degree. C. with stirring and introduction of air. Reaction time
at 90.degree. C.: 6 h. It was then cooled to about 60.degree. C.
and the sodium hydroxide in solution in water, for neutralizing the
sulphuric acid catalyst, and also the methanol, for esterifying the
unreacted methacrylic anhydride, were added. This was followed by
stirring at 60.degree. C. for 1 h, after which the batch was poured
as thin jet, with stirring (metallic paddle stirrer, stirring
motor), into 3 l of water. The mixture was stirred for 0.5 h and
the precipitate was then isolated by suction on a glass filter
frit, washed with twice 2 l of water, and subsequently subjected to
preliminary drying with air on the suction filter. The solid was
subsequently dried in air.
[0030] Yield: 924.6 g (99.4% of theory)
[0031] Analyses: water content: 0.08%
[0032] hydroquinone monomethyl ether: 6 ppm
[0033] 2,4-dimethyl-6-tert-butylphenol: 174 ppm
Gas chromatography:
[0034] 0.047% methyl methacrylate
[0035] 0.013% methacrylic acid
[0036] 0.637% 4-hydroxybenzophenone
[0037] 97.56% 4-(methacryloyloxy)benzophenone
[0038] Pt--Co colour number as 20% strength solution in acetone:
150
Example 2
Apparatus:
[0039] 4 l four-neck round-bottomed flask with mechanical stirrer,
reflux condenser, Pt100 temperature sensor, air introduction tube,
Anschutz attachment, dropping funnel, electrically heated oil
bath
Batch:
[0040] 1.5 mol of 4-hydroxybenzophenone: 303 g
[0041] 1.65 mol of methacrylic anhydride (stabilized with 2000 ppm
of 2,4-dimethyl-6-tert-butylphenol): 262 g
[0042] 0.0087 mol of concentred sulphuric acid: 0.84 g
[0043] 798 mg of hydroquinone monomethyl ether
[0044] 399 mg of 2,4-dimethyl-6-tert-butylphenol
Procedure:
[0045] The batch was weighed out completely and then heated to
90.degree. C. with stirring and introduction of air. Reaction time
at 90.degree. C.: 6 h. It was then cooled to about 60.degree. C.
and the sodium hydroxide in solution in water, for neutralizing the
sulphuric acid catalyst, and also the methanol, for esterifying the
unreacted methacrylic anhydride, were added. The batch was
subsequently stirred at 60.degree. C. for 1 h and then admixed with
1566 g of methyl methacrylate, with stirring. The resulting
solution was cooled to room temperature with stirring, and
filtered. The solution of the 4-(methacryloyloxy)benzophenone in
methyl methacrylate has the following composition as determined by
gas chromatography:
[0046] 56.016% methyl methacrylate
[0047] 6.954% methacrylic acid
[0048] 2.399% 4-hydroxybenzophenone
[0049] 32.717% 4-(methacryloyloxy)benzophenone.
[0050] The water content is 0.27%; the stabilizer content is 113
ppm of 2,4-dimethyl-6-tert-butylphenol and 4 ppm of hydroquinone
monomethyl ether. The Pt--Co colour number is 169.
* * * * *